Fixation device and multiple-axis joint for a fixation device

ABSTRACT

A fixator system includes an active strut that that can be gradually or acutely adjusted. Adjustments can be made in six degrees of freedom. Embodiments of the active strut can provide for two of the six degrees of freedom being about a first common point of rotation, and another two of the six degrees of freedom being about a second common point of rotation. Embodiments of the fixator can include one or more active struts in combination with one or more passive struts. The passive struts can be rigidly locked or can be unlocked so as to be freely and acutely adjustable while gradual or acute adjustments are made using the one or more active struts.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. application Ser. No.12/618,498, which was filed on Nov. 13, 2009 and is incorporated hereinby reference.

TECHNICAL FIELD

The present disclosure relates in general to medical device technology,and more specifically to external fixation devices and to drive systemsthat allow precise control for positioning and locking such fixationdevices.

BACKGROUND

Without limiting the scope of the present disclosure, its background isdescribed in connection with external fixation devices. Generally,external fixation devices are commonly used on both the upper and lowerlimbs for both adults and children in a variety of surgical proceduresincluding limb lengthening, deformity correction and treatment offractures, mal-unions, non-unions and bone defects.

One common external fixation device is known as the Ilizarov Apparatus.The Ilizarov external fixation procedure involves a rigid frameworkconsisting of several rings or arches that are placed externally aroundthe limb and attached to injured (e.g., due to fracture) or surgicallyseparated (e.g., for limb lengthening and deformity correction) bonesegments using special bone fasteners (wires and pins) inserted into thebone segment and connected to the related section of the external rigidframework. The opposite rings of the rigid framework are connected byeither threaded or telescopic connection rods or by assembled uni-planaror multi-planar angular hinges, which allow the surgeon to adjust therelative position of the rings to each other longitudinally or angularlyover a period of time. This allows new bone to gradually form in the gapbetween bone segments created by this distraction technique. Once thedesired position of bone segments is achieved over the course of time(e.g., 2-6 weeks), the external apparatus is stabilized into a fixedposition and left on the bone segments until the fracture is healed ornewly formed bone is completely or substantially mineralized, whichcould take up to an additional 3-6 months, depending on the nature ofpathology and degree of deformity.

Another common external fixation device is a Taylor Spatial Frame asdescribed in U.S. Pat. Nos. 6,030,386, 5,891,143, and 5,776,132. TheTaylor Spatial Frame is a hexapod type of device based on a Stewartplatform but shares many components and features of the Ilizarovapparatus. The Taylor Spatial Frame consists of two external fixatorrings attached to bone segments by wires or half pins and connectedtogether by six struts that may be lengthened or shortened as necessary.Adjustment of strut lengths allows manipulation of the bone segments in6 axes (e.g., lengthening/shortening, external/internal rotation,anterior/posterior horizontal translation, medial/lateral horizontaltranslation, anterior/posterior angular translation, and medial/lateralangular translation) to correct linear, angular and rotationaldeformities simultaneously.

The fixation device would usually be placed on the affected patient bymedical personnel in such a way as to align the affected body partduring the healing process, holding the affected body part in the properposition for treatment. Since applications of such devices can include awide variety of deformities, body sites, and surgical implementations,there is a need for fixation devices that can initially be acutelyadjusted in order to accommodate such variabilities and subsequentlymaintain the affected body part in one desirable position. Moreover, atypical treatment regimen requires frequent adjustments to be performedby the patient and/or during repeated visits to medical professionals sothat the fixation device could be periodically and gradually adjusted,providing the desired orientation to the affected body part and settingthe proper amount of stretching and support for healing. Accordingly,there is also a need for fixation devices that allow for gradualadjustments after the fractured body part is substantially maintained inone position.

Thus, there is a need for an improved fixation device that will allowmedical professionals to make effective, calibrated adjustments to thepositioning of the injured body part.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent disclosure, reference is now made to the detailed descriptionalong with the accompanying figures and in which:

FIG. 1 is a perspective view of an external fixator ring systemaccording to one embodiment of the present disclosure that includes anactive strut in combination with a plurality of passive struts;

FIG. 2 is a perspective view of a fixator assembly according to oneembodiment of the present disclosure;

FIG. 3A is a perspective view of a first embodiment of a multiple-axisjoint according to the present disclosure;

FIG. 3B is a cross-sectional view of a portion of the first embodimentof the multiple-axis joint taken along section lines 3B-3B shown in FIG.3A;

FIG. 3C is a cross-sectional view of a portion of the first embodimentof the multiple-axis joint taken along section lines 3C-3C shown in FIG.3B;

FIG. 3D is a top view of a portion of the first embodiment of themultiple-axis joint shown in FIG. 3B;

FIG. 4A is a perspective view of a second embodiment of a multiple-axisjoint according to the present disclosure;

FIG. 4B is a partially-sectioned view of a portion of the joint shown inFIG. 4A;

FIG. 5A is a perspective view of a third embodiment of a multiple-axisjoint according to the present disclosure;

FIG. 5B is a view of an internal joint of the third embodiment of themultiple-axis joint shown in FIG. 5A;

FIG. 5C is a partially-sectioned view of the internal joint shown inFIG. 5B;

FIG. 6A is a perspective view of a fourth embodiment of a multiple-axisjoint according to the present disclosure;

FIG. 6B is a top view of a portion of the joint shown in FIG. 6A;

FIG. 7 is a view of an internal joint of the fourth embodiment of themultiple-axis joint shown in FIG. 6;

FIG. 8 is a perspective view of a fifth embodiment of a multiple-axisjoint according to the present disclosure;

FIG. 9 is a view of an internal joint of the fifth embodiment of themultiple-axis joint shown in FIG. 8;

FIG. 10A is a perspective view of a sixth embodiment of a multiple-axisjoint according to the present disclosure;

FIG. 10B is a view of a gear assembly and acute adjustment assembly ofthe sixth embodiment of the multiple-axis joint shown in FIG. 10A;

FIG. 11 is a view of an alternative gear assembly and acute adjustmentassembly of the sixth embodiment of the multiple-axis joint shown inFIGS. 10A and 10B;

FIG. 12 is a perspective view of a first alternative embodiment of anexternal fixator ring system according to the present disclosure thatincludes a plurality of active struts;

FIG. 13 is a perspective view of a second alternative embodiment of anexternal fixator ring system according to the present disclosure thatincludes a plurality of active struts in combination with a plurality ofpassive struts;

FIG. 14A is a perspective view of an embodiment of a passive supportstrut that can be used with external fixator ring systems of the presentdisclosure;

FIG. 14B is a perspective view of internal elements of the passivesupport strut shown in FIG. 14A;

FIG. 14C is an partially-sectioned view of elements of the passivesupport strut shown in FIG. 14B; and

FIG. 15 is a perspective view of another embodiment of a passive supportstrut that can be used with external fixator ring systems of the presentdisclosure.

DETAILED DESCRIPTION

While the making and using of various embodiments of the multiple-axisjoint according to the present disclosure are discussed in detail below,it should be appreciated that the present application provides manyapplicable inventive concepts that can be embodied in a wide variety ofspecific contexts. Without limiting the scope of the present disclosure,the multiple-axis joint is described in connection with externalfixation devices. However, the multiple-axis joint can be used withother devices. The specific embodiments discussed herein are merelyillustrative of specific ways to make and use the multiple-axis jointdisclosed herein and do not delimit the scope of the application, andtheir usage does not delimit the application, except as outlined in theclaims.

FIG. 1 is a perspective view of an external fixator ring system 100. Thefixator ring system 100 includes a first fixator ring 102 a and a secondfixator ring 102 b, which serve as examples of fixator base elements.The fixator rings 102 a and 102 b both include a plurality of strutmounting positions 104. The fixator rings 102 a and 102 b are connectedby a plurality of connection struts 106, 108, and 110, which areattached to the fixator rings 102 a and 102 b at the strut mountingpositions 104.

Strut 106 is an active strut, whereas struts 108 and 110 are passivestruts. All of the struts 106, 108, and 110 are preferably capable ofbeing locked into a rigid state such that the rings 102 a and 102 b arefixed relative to each other, and unlocked into a free state such thatacute adjustments can be made to the relative positions of the rings 102a and 102 b. Such acute adjustments are desirable at certain times, forexample during the initial placement of the fixator ring system 100 ontoan injured limb. The passive struts 108 and 110 are limited to beingeither locked into a passive locked state, which is a non-adjustablerigid state, or being unlocked into a freely adjustable state. Theactive strut 106 is capable of being locked into an active locked state,which is a rigid and adjustable state, or being unlocked into a freelyadjustable state. In some embodiments, the active strut 106 can furtherbe locked into a passive locked state so that it is even locked frombeing adjustable. Thus, the active strut 106 differs from the passivestruts 108 and 110 in that the active strut 106 is configured for anactive locked state wherein the active strut 106 is capable of beingcontrollably articulated for making fine or gradual adjustments to therelative positions of the rings 102 a and 102 b with little or no lossin rigidity while such adjustments are made. Such fine or gradualadjustments between the rings 102 a and 102 b are desirable after theinitial placement of the fixator ring system 100, for example as part ofa treatment plan for an injured limb that might require periodic gradualadjustments. Thus, the fixator ring system 100 disclosed herein includesa combination of active and passive struts 106, 108, and 110. While thefixator ring system 100 includes one active strut 106 and two passivestruts 108 and 110, alternative embodiments, including those describedherein, can include more than one active strut and more or fewer thantwo passive struts.

The first fixator ring 102 a includes a top surface 112 and an opposingbottom surface (not shown). The top surface 112 includes numerous holes116 that extend through the top surface 112 to the bottom surface (notshown). The holes 116 may be used for attachment of wire and half-pinfixation elements (bolts), threaded or telescopic connection rods,plates, posts or other device connection elements to the first fixatorring 102 a. In some embodiments, the outer side surface 120 of the firstfixator ring 102 a can include numerous threaded apertures (not shown)that provide additional attachment points for struts or other connectionelements (not shown). The second fixator ring 102 b can be identical orsimilar to the first fixator ring 102 a.

Although the shape of the fixator rings 102 a and 102 b as shown FIG. 1is substantially circular, the shape of the fixator rings 102 a and 102b can vary to accommodate the physical contour of various body parts towhich the fixation system 100 would be attached. For example, thefixator rings 102 a and 102 b can be fixator base elements that areconfigured to have an oval shape, D-shape, U-shape, C-shape, a polygon,or other irregular shapes. In some exemplary embodiments, an ellipticalfixator ring (not shown) may be particularly advantageous. The insertionof pins or wires into a patient's limb can cause the surrounding tissueto swell unevenly, and in such a case, an elliptical fixator ring canaccommodate the uneven swelling better than a circular ring can. Thefixator rings 102 a and 102 b may be fixator base elements that form acomplete ring (full ring) or a segment or portion of a ring (e.g., halfring, ⅓ ring, ¼ ring, ⅜ ring, ⅝ ring, ⅔ ring, ¾ ring, and other) that iseither used alone or joined with other segments or portions of the ringto form a fixator ring (not shown). The fixator rings 102 a and 102 bmay be fixator base elements that are constructed of any material thatprovides the structural rigidity necessary for fixation such as metal,alloy, carbon fiber, plastic, ceramic and so forth. Moreover, thematerial comprising the rings 102 a and 102 b may be radiotranslucent.

The strut 106 is an active strut that is adjustable in six degrees offreedom. The strut 106 includes a first joint 122 and a second joint 124connected by a center portion 126. The first joint 122 includes a firstdriven element 128 that connects to one of the strut mounting positions104 of the first fixator ring 102 a. The second joint 124 includes asecond driven element 130 that connects to one of the strut mountingpositions 104 of the second fixator ring 102 a. As discussed in greaterdetail below, the driven elements 128 and 130 can each be articulated intwo degrees of freedom. For example, depending on the embodiment, thedriven element 128 can be angularly and/or rotationally repositionedrelative to the center portion 126 of the strut 106 and/or the drivenelement 130 can be angularly and/or rotationally repositioned relativeto the center portion 126 of the strut 106. The center portion 126 canalso be lengthwise adjustable and/or translationally and/or rotationallyadjustable relative to one or both of the first and second joints 122and 124. Such embodiments can allow for multiple degrees of freedom inrepositioning the first fixator ring 102 a relative to the secondfixator ring 102 b.

FIG. 2 is a perspective view of a fixator assembly 200. The fixatorassembly 200 can be used as the strut 106 of the fixator ring system100, or can be used as a monolateral fixator. The fixator assembly 200includes the first joint 122 and the second joint 124 as describedabove. The first and second joints 122 and 124 are connected by thecenter portion 126. The first joint 122 includes the driven element 128that can be configured for connection to another fixator base element,such as the fixator ring 102 a or 102 b, or another type of fixator baseelement. As discussed in greater detail below, the driven element 128can be angularly and/or rotationally repositioned relative to the centerportion 126 of the fixator assembly 200, as illustrated by arrows A andB.

The fixator assembly 200 can include various other adjustable elementsin order to allow for six degrees of freedom. For example, the fixatorassembly 200 can include internal worm gears at adjustment position 202for allowing adjustments to be made in directions indicated by arrows Cand D; rack and pinion gears at adjustment position 204 for allowingadjustments to be made in directions indicated by arrow E; androtational gearing at adjustment position 206 for allowing adjustmentsto be made in directions indicated by arrow F. The adjustable elementsused to provide for adjustments in directions indicated by arrows C, D,E, and F can be selected from among a variety of know adjustmentsystems.

As described in greater detail below, a technician can lock the firstjoint 122 in a locked state where the driven element 128 is not free tomove relative to other portions of the joint or fixator assembly 200.The technician can unlock the first joint 122 or otherwise place thefirst joint into an unlocked state for acute adjustments of the fixatorassembly. In some embodiments, the first joint 122 can also be placedinto a gradual-adjustment state for finer, more controlled movement andcorrection over time. The joint 122 can be manipulated either by hand orby a wrench on either one or multiple faces of the joint housing.Combining the two joint 122 with a strut body such as the center portion126 and the second joint 124 can effectively allow for movement of twobone segments, fixator base elements, or other elements through sixdegrees of freedom.

The joint used as the first joint 122, and also as the second joint 124in some embodiments, can be selected from the various embodiments ofmultiple-axis joints described in the present disclosure. Embodiments ofthe joint 122 can include a captured joint that can be driven in twodegrees of freedom in order to achieve angulations and/or rotationsabout a single point in space. Embodiments can include a ball, which canbe an at least partially spherically-shaped element, which may be hollowor solid, and which may have flat regions, projections, depressions,elements that extend therefrom and/or regions that are threaded,slotted, and/or otherwise provided with asperities. Embodiments of thejoint 122 can include such a ball or nested ball/cylinder assembly thatis securely captured in a housing such that a driven element can beoriented within a conical envelope protruding outward from the center ofrotation. The ball or ball/cylinder assembly can be directly acted on bya driving mechanism (various exemplary forms detailed herein) that canbe either automated or manually operated in order to achieve rotationand/or angulation of the ball itself. This joint can be used as part ofan external fixator in order to move a fixator base element, bonesegment, or other attachment through these degrees of freedomaccurately.

Thus, the fixator assembly 200 constitutes an example of a single strutthat can used in a monolateral configuration with attachments connectedto each end thereof that could connect to a fixation element, such as ahalf-pin. First, fixation elements are inserted and attached to bonesegments. Second, the fixator assembly 200 is unlocked and each end caninclude a driven element 128 that is attached to the appropriatefixation element and acute adjustment would be made, if necessary.Third, the fixator assembly 200 would be locked to hold the bonesegments in place. Next, gradual adjustments could be made over time byunlocking the assembly 200, adjusting the driven elements 128, and thenonce again locking the assembly 200. This gradual adjustment over timecould move two bone segments relative to each other in all six degreesof freedom.

FIGS. 3A through 3D show a first embodiment of a multiple-axis joint,generally designated as multiple-axis joint 300. FIG. 3A shows aperspective view of the joint 300. The joint 300 includes a ball joint302 captured within a housing 304. The ball joint 302 includes a ball306, which serves as an example of a spherically-shaped element. FIG. 3Bshows a cross-sectional view of the ball 306 taken along section lines3B-3B shown in FIG. 3A. FIG. 3C shows a cross-sectional view of the ball306 taken along section lines 3C-3C shown in FIG. 3B. FIG. 3D shows atop view of the ball 306, illustrating the axes of rotation.

The ball 306 includes two sets of gear teeth 308 and 310. The gear teeth308 and 310 are cut into the ball 306, for example in a radial orcircumferential configuration, and extend in respective directions thatare 90 degrees from one another. A first gear 312 is mated with thefirst set of gear teeth 308. A second gear 314 is mated with the secondset of gear teeth 310. A driven element 316 is rigidly attached to theball 306 and extends out of the housing 304 through a slot 318. Rotationof the first gear 312 will rotate the ball 306 within the housing 304.Rotation of the second gear 314 will angulate the ball 306 within thehousing 304.

Depending on the embodiment, the first and second gears 312 and 314 canbe rotated, directly or indirectly, by the technician in order to adjustthe position of the driven element 316. In some embodiments, the gears312 and 314 can be connected, directly or indirectly, to respectiveknobs, handles, or the like that can be used by the technician foradjusting the position of the driven element 316. In some embodiments,the gears 312 and 314 can be configured to be drivable, directly orindirectly, by a removable tool such as a hex key, screwdriver, or othertool that a technician can use in order to adjust the position of thedriven element 316. For example, each of the gears 312 and 314 caninclude a slot or the like, and the housing 300 can include an accesshole through which a tool can be inserted and mated with the gears 312and 314 so that the technician can rotate the gears 312 and 314, andthereby adjust the position of the driven element 316. In someembodiments, each of the gears 312 and 314 can be attached to arespective drive shaft that extends from the gear 312, 314 and can berotated either directly or using a removable tool such that rotation ofthe drive shafts adjusts the position of the driven element 316. Stillfurther embodiments can include any desired configuration for allowing atechnician to perform an action that causes rotation of selected gears312 and 314 so that the technician can adjust the position of the drivenelement 316.

The first gear 312 can be rotated for driving the ball 306 such that thedriven element 316 is rotationally articulated about a first axis ofrotation 320 in directions indicated by arrows 322. As the first gear312 is rotated, the ball 306 rotates and the gear teeth 310 slide withinthe gear teeth of the second gear 314, thereby allowing rotation of thedriven element 316 independently of angulation of the driven element316. The second gear 314 can be rotated for rotating the ball 306 abouta second axis of rotation 326 such that the driven element 316 isangularly articulated, angulating the first axis of rotation 320,thereby moving the driven element in directions indicated by arrows 324.As the second gear 314 is rotated, the ball 306 rotates and the gearteeth 308 slide within the gear teeth of the first gear 312, therebyallowing angulation of the driven element 316 independently of rotationof the driven element 316. As shown in FIG. 3D, the first and secondaxes 320 and 326 extend through the center of the ball 306. The firstaxis of rotation 320 extends through the center of the ball 306 in adirection that is at least substantially perpendicular to the secondaxis of rotation 326. The first and second axes of rotation 320 and 326intersect at a common rotation point about which the driven element 316can be driven in two directions or degrees of freedom. The commonrotation point is preferably at, or substantially near, the center ofthe ball 306, thus allowing the driven element 316 to be intuitivelyadjusted in two degrees of freedom that intersect at a common point ofrotation that is at or substantially near the center of the ball 306.Note that the first set of gear teeth 308 on top of ball 306 are notshown in FIG. 3D so that the first and second axes of rotation 320 and326 can be more clearly shown.

In some embodiments, the gears 312 and 314 can be repositioned relativeto the ball 306 so as to be in contact with the ball 306 in a firstposition as shown in FIG. 3A, and to be out of contact with the ball 306in a second position. For example, in some embodiments, the gears 312and 314 can be slid or otherwise moved in and out of contact with theball 306. When the gears 312 and 314 are in contact with the ball 306,the gears 312 and 314 act as a break to prevent movement of the ball 306unless one or both of the gears 312 and 314 are rotating to drive theball 306. Thus, when the gears 312 and 314 are in contact with the ball306, the gears 312 and 314 act to effectively lock the joint 300.However, once the gears 312 and 314 are moved out of contact with theball 306 such that the first gear 312 is no longer mated with the firstset of gear teeth 308 and the second gear 314 is no longer mated withthe second set of gear teeth 310, the ball 306 can freely move, thusallowing for acute adjustments of the position of the driven element316.

FIGS. 4A and 4B show a second embodiment of a multiple-axis joint,generally designated as multiple-axis joint 400. FIG. 4A shows aperspective view of the joint 400. The joint 400 can be similar to joint300, but includes a self-finding arm mechanism 402 in place of one ofthe gears and sets of gear teeth of joint 300. In alternativeembodiments, the self-finding arm mechanism 402 can be in addition tothe use the gears and sets of gear teeth of joint 300 discussed above.

The joint 400 can include a housing, such as housing 304; however, thehousing is not shown in FIG. 4 for purposes of clarity. The joint 400includes a ball joint 402. The ball joint 402 includes a ball 406, whichserves as an example of a spherically-shaped element. The ball 406includes a set of gear teeth 410. The gear teeth 410 are cut into theball 406, for example in a radial or circumferential configuration. Agear 414 is mated with the set of gear teeth 410.

The joint 400 incorporates the usage of the gear 414 to angulate theball 406 and the arm mechanism 402 to rotate the ball 406. The armmechanism 402 includes an arm 420 that acts within a slot 422 in the topof the ball 406. FIG. 4B shows a partially-sectioned view illustrating aview of the arm 420 within the slot 422. Rotation of the arm 420 rotatesthe ball about the first axis of rotation 320 as shown in FIG. 3D,whereas the gear 414 rotates the ball about the second axis of rotation326 as shown in FIG. 3D. The arm 420 includes a first arm section 420 aand a second arm section 420 b connected by a joint 424. The joint 424can incorporate a universal joint, a ball and socket, or other mechanismto allow for the arm 420 to rotate the ball 406 about the first axis ofrotation 320. A driven element 426 is rigidly attached to the ball 406and extends out of the housing (not shown).

Thus, the ball 406 can include the same first and second axes ofrotation 320 and 326 as shown in FIG. 3D in connection with ball 306.When the arm 420 is rotated, the gear teeth 410 in the bottom of theball 406 can slide within the gear 414, allowing rotation of the ball406 about the first axis of rotation 320 independently of angulation ofthe driven element 406. When the gear 414 is rotated, the joint 424 inthe arm mechanism 402 can pivot as the ball 406 is rotated about thesecond axis of rotation 326, allowing angulation of the driven element406 independently of rotation of the driven element 406.

In some embodiments, the gear 414 and arm mechanism 402 can berepositioned relative to the ball 406 so as to be in contact with theball 406 in a first position as shown in FIG. 4, and to be out ofcontact with the ball 406 in a second position. For example, in someembodiments, the gear 414 and arm mechanism 402 can be moved in and outof contact with the ball 406. When the gear 414 and arm mechanism 402are in contact with the ball 406, the gear 414 and arm mechanism 402 actas a break to prevent movement of the ball 406 unless one or both of thegear 414 and arm mechanism 402 are driving rotation of the ball 306.Thus, when the gear 414 and arm mechanism 402 are in contact with theball 406, the gear 414 and arm mechanism 402 act to effectively lock thejoint 400. However, once the gear 414 and arm mechanism 402 are movedout of contact with the ball 406 such that the arm mechanism 402 is nolonger mated with the slot 422 and the gear 414 is no longer mated withthe set of gear teeth 410, the ball 406 can freely move, thus allowingfor acute adjustments of the position of the driven element 406.

FIGS. 5A through 5C show a third embodiment of a multiple-axis joint,generally designated as multiple-axis joint 500. FIG. 5A shows aperspective view of the joint 500. The joint 500 can be similar to joint300, but incorporates an internal joint 502 placed at the center of aball joint 506 to perform rotation in place of one of the gears and setsof gear teeth of joint 300. FIG. 5B shows a view of the internal joint502, and FIG. 5C shows a partially-sectioned view of the internal joint502.

The joint 500 includes a housing 504, and a ball joint 506 capturedwithin the housing 504. The ball joint 506 includes a ball 508, whichserves as an example of a spherically-shaped element. The ball 508includes a set of gear teeth 510. The gear teeth 510 are cut into theball 508, for example in a radial or circumferential configuration. Agear 514 is mated with the set of gear teeth 510. The joint 500incorporates the use of the gear 514 to angulate the ball 508 and theinternal joint 502 to rotate the ball 508.

The internal joint 502 can be controlled by a control arm 520 thatconnects to a universal joint, a ball and socket joint, a torqueshaft/wire, or other mechanism suitable for rotating the driven element526. For example, as shown in FIGS. 5B and 5C, the internal joint 502can include an inner ball 530 and an outer ball 532, which serve asexamples of spherically-shaped elements. Note that the ball 508 is notshown in FIG. 5C so that the internal joint 502 can be more clearlyshown. The outer ball 532 is rigidly connected to the control arm 520,and the inner ball 530 is rigidly connected to the driven element 526.The outer ball 532 includes a pin 534 that extends through the innerball 530. The pin 534 acts on the inner ball 532 such that the innerball 532 rotates about the longitudinal axis of the driven element 526,corresponding to the first axis 320 shown in FIG. 3D, when the controlarm 520 is rotated. In some embodiments, the inner ball 532 can be fixedrelative to the ball 508 such that the ball 508 also rotates as thecontrol arm 520, inner ball 530, and driven element 526 are rotated. Insuch embodiments, the driven element 526 can be attached to the ball 508instead of to the inner ball 530 as shown in FIG. 5C, and the inner ball530 can be fixed to the ball 508. In other embodiments, the inner ball530 and driven element 526 can be free to rotate relative to the ball508. In such embodiments, the driven element 526 can be fixed to theinner ball 530 as shown in FIG. 5C and pass through a hole through theball 508.

The ball 506 can include the same first and second axes of rotation 320and 326 as shown in FIG. 3D in connection with ball 306. When thecontrol arm 520 is rotated, the gear teeth 510 in the bottom of the ball506 can slide within the teeth of gear 514, allowing rotation of theball 508 about the first axis of rotation 320 independently ofangulation of the driven element 526. When the gear 514 is rotated, thegear 514 drives the ball 506 to rotate about the second axis of rotation326, allowing angulation of the driven element 526 independently ofrotation of the driven element 526. When the gear 514 is rotated, theinternal joint 502 can pivot about pin 534, allowing angulationindependently of rotation.

FIGS. 6A, 6B, and 7 show a fourth embodiment of a multiple-axis joint,generally designated as multiple-axis joint 600. FIG. 6A shows aperspective view of the joint 600. The joint 600 incorporates a balljoint 602 that includes an outer ball 604 and a driven element 606.Outer ball 604 serves as an example of a spherically-shaped element.FIG. 6B shows a top view of the outer ball 604, illustrating the axes ofrotation 620 and 626 about which joint 600 can drive the driven element606. The driven element 606 extends in a more generally verticaldirection compared to the driven elements 316, 426, and 526 of the firstthrough third embodiment joints 300, 400, and 500, respectively, whichextend in a generally horizontal direction in a manner similar to thedriven element 128 used with fixators 100 and 200 shown in FIGS. 1 and2, respectively. This generally vertical orientation provides increasedstrength in tension and compression as compared to the more horizontalarrangement of the first through third embodiment joints 300, 400, and500.

In the fourth embodiment, rotation of the ball joint 602 causesangulations of the driven element 606 in two degrees of freedom. Thus,unlike the first through third embodiments that include a first axis ofrotation 320 that is coaxial with the driven element, the fourthembodiment joint 600 includes first and second axes of rotation 620 and626 that are perpendicular to each other and to the longitudinal axis ofthe driven element 612. The first and second axes of rotation 620 and626 intersect at a common rotation point about which the driven element606 can be driven in two directions or degrees of freedom. The commonrotation point is preferably at, or substantially near, the center ofthe outer ball 604, thus allowing the driven element 606 to beintuitively adjusted in two degrees of freedom that intersect at acommon point of rotation that is preferably at or substantially near thecenter of the outer ball 604.

The ball joint 602 is captured within a housing 608. FIG. 7 shows theball joint 602 without the housing 608 and other elements of the joint600, and also shows portions of the ball joint 602 located within theouter ball 604. The ball joint 602 includes an inner ball 610 disposedconcentrically within, and free to move relative to, the outer ball 604.The inner ball 610 serves as an example of a spherically-shaped element.The outer ball 604 can be driven to rotate in order to angulate thedriven element 606 about the first rotational axis 620, while the innerball 610 can be driven to rotate independently of the outer ball 604 forangulating the driven element 606 about the second rotational axis 626.

A first drive arm 612 is attached to the inner ball 610 such that theinner ball 610 rotates as the first drive arm 612 rotates about thelongitudinal axis of the first drive arm 612, which corresponds to thesecond rotational axis 626. The driven element 606 is attached to theinner ball 610 and extends through the outer ball 604 through a slot 604a in the outer ball 604. The slot 604 a defines a range of motion of thedriven element 606 when driven by the first drive arm 612. The firstdrive arm 612 is pivotally attached to the inner ball 610, such that thefirst drive arm 612 is free to pivot relative to the inner ball 610 asindicated by arrow 614. As shown in FIG. 6, the first drive arm 612 canbe driven by a first gear assembly 616. In alternative embodiments, thefirst gear assembly 616 can be replaced by a belt drive, a chain andsprocket drive, a torque shaft, a cable drive, or other such mechanisms.

A second drive arm 620 is rigidly attached to the outer ball 604 suchthat the outer ball 604 rotates as the second drive arm 620 rotatesabout the longitudinal axis of the second drive arm 612, whichcorresponds to the first rotational axis 620. The outer ball 604 can bedriven by a second gear assembly 618. As shown in FIG. 6, the seconddrive arm 620 can be driven by a second gear assembly 616. Inalternative embodiments, the second gear assembly 618 can be replaced bya belt drive, a chain and sprocket drive, a torque shaft, a cable drive,or other such mechanisms.

FIGS. 8 and 9 show a fifth embodiment of a multiple-axis joint,generally designated as multiple-axis joint 700. FIG. 8 shows aperspective view of the joint 700. The joint 700 includes a cylinder 702captured within a housing 704. FIG. 9 shows a partially sectioned viewof the cylinder 702, illustrating a ball joint 706 disposed within thecylinder 702.

The ball joint 706 includes a ball 708, which serves as an example of aspherically-shaped element, rigidly attached to a driven element 710.The joint 700 incorporates the ball joint 706 such that the drivenelement 710 extends in a generally vertical direction, similar to thefourth embodiment joint 600. The ball joint 706 also includes a firstdrive arm 712. The first drive arm 712 is attached to the ball 708 suchthat the ball 708 rotates as the first drive arm 712 rotates about thelongitudinal axis of the first drive arm 712. The first drive arm 712 ispivotally attached to the ball 708, such that the first drive arm 712 isfree to pivot relative to the ball 708 as indicated by arrow 714. Thedriven element 710 is attached to the ball 708 and extends through thecylinder 702 through a slot 702 a in the cylinder 702. The slot 702 adefines a range of motion of the driven element 710 when driven by thefirst drive arm 712.

The rotational axis of joint 700 are like those of the fourth embodimentjoint 600 shown in FIG. 6B. Thus, the joint 700 includes first andsecond axes of rotation 620 and 626 that are perpendicular to each otherand to the longitudinal axis of the driven element 710. The first andsecond axes of rotation 620 and 626 intersect at, or substantially near,the center of the cylinder 702, thus allowing the driven element 710 tobe intuitively adjusted in two degrees of freedom that intersect at orsubstantially near the center of the cylinder 702. The ball 708 isdisposed within, and free to move relative to, the cylinder 702. Thecylinder 702 can be driven to rotate in order to angulate the drivenelement 710 about the first axis of rotation 620, while the ball 708 canbe driven to rotate independently of the cylinder 702 for angulating thedriven element 710 about the second axis of rotation 626.

The first drive arm 712 is rigidly attached to the ball 708 and can bedriven by a first gear assembly 716. The first gear assembly 716includes a first gear 718 that is rigidly attached to the first drivearm 712 such that the first drive arm 712 rotates with the first gear718. The first gear assembly 716 also includes a first rack member 720.The first rack member 720 is a cylindrically cut rack having at leastone threaded end 722. In addition, or alternatively, the first rackmember 720 can have a second threaded end (not shown). The threaded end722 mates with similar threads within the housing 704 such that rotationof the first rack member 720 about its longitudinal axis causes thefirst rack member 720 to move translationally along its longitudinalaxis. The first rack member 720 can travel translationally and berotated at the same time, allowing gear teeth of the first gear 718 toslide along the cylindrical cuts of the first rack member 720 as thefirst rack member 720 travels, thereby causing the first gear 718 torotate. Rotation of the first gear 718 rotates the first drive arm 712,which in turn rotates the ball 708, which results in angulation of thedriven element 710 about the second axis of rotation 626. In alternativeembodiments, the first gear assembly 716 can be replaced by a beltdrive, a chain and sprocket drive, a torque shaft, a cable drive, orother such mechanisms. When the first rack member 720 is not beingrotated, the threaded end 722 acts as a braking/holding mechanism withthe threads providing the braking force in the direction parallel to thelongitudinal axis of the first rack member 720. Thus, when the firstrack member 720 is not being rotated, the first rack member 720 acts tolock the first gear 718 so that the first gear 718 cannot rotate,thereby preventing the ball 708 from angulating the driven element 710.In alternative embodiments, the rack member 720 can be cut at an anglerather than cut cylindrically, for example the rack member 720 can be aworm or include a worm portion, and in such embodiments the gear 718 canbe a worm gear.

A second drive arm 732 is rigidly attached to the cylinder 702 can bedriven by a second gear assembly 736. The second gear assembly 736includes a second gear 738 that is rigidly attached to the second drivearm 732 such that the second drive arm 732 rotates with the second gear738. The second gear assembly 736 also includes a second rack member740. The second rack member 740 is a cylindrically cut rack having atleast one threaded end 742. In addition, or alternatively, the secondrack member 740 can have a second threaded end 744. The threaded end 742and/or 744 mates with similar threads within the housing 704 such thatrotation of the second rack member 740 about its longitudinal axiscauses the second rack member 740 to move translationally along itslongitudinal axis. The second rack member 740 can travel translationallyand be rotated at the same time, allowing gear teeth of the second gear738 to slide along the cylindrical cuts of the second rack member 740 asthe second rack member 740 travels, thereby causing the second gear 738to rotate. Rotation of the second gear 738 rotates the second drive arm732, which in turn rotates the cylinder 702, which results in angulationof the driven element 710 about the first axis of rotation 620. Inalternative embodiments, the second gear assembly 736 can be replaced bya belt drive, a chain and sprocket drive, a torque shaft, a cable drive,or other such mechanisms. When the second rack member 740 is not beingrotated, the threaded end 742 acts as a braking/holding mechanism withthe threads providing the braking force in the direction parallel to thelongitudinal axis of the second rack member 740. Thus, when the secondrack member 740 is not being rotated, the second rack member 740 acts tolock the second gear 738 so that the second gear 738 cannot rotate,thereby preventing the cylinder 702 from angulating the driven element710. In alternative embodiments, the rack member 740 can be cut at anangle rather than cut cylindrically, for example the rack member 740 canbe a worm or include a worm portion, and in such embodiments the gear738 can be a worm gear.

FIGS. 10A and 10B show a sixth embodiment of a multiple-axis joint,generally designated as multiple-axis joint 800. FIG. 10A shows aperspective view of the joint 800. The joint 800 can be substantiallythe same as joint 700, except for differences in the gear assembliesdiscussed below. The joint 800 includes a housing 704 as shown in FIG.8. The joint 800 also includes a cylinder 702 and a ball joint 706 asshown in FIG. 9 and described in connection with joint 700. Elements ofthe joint 800 that can be the same or substantially the same ascorresponding elements of joint 700 have retained the same elementnumbers, and the description of those like-numbered elements inconnection with joint 700 applies equally to joint 800.

The joint 800 includes a first drive arm 712 rigidly attached to theball 708 and a second drive arm 732 rigidly attached to the cylinder 702as shown in FIGS. 8 and 9. A first gear assembly 802 includes a firstgear 718 that is rigidly attached to the first drive arm 712. A secondgear assembly 804 and a second gear 738 is rigidly attached to thesecond drive arm 732. The first and second gears 718 and 738 canangulate the driven element 710 as described above in connection withjoint 700 about first and second rotational axes 620 and 626.

FIG. 10B shows an enlarged block diagram of the second gear assembly804, as well as a portion of first gear assembly 802. The first andsecond gear assemblies 802 and 804 both allow for acute and finer ormore gradual adjustments. The first and second gear assemblies 802 and804 can be substantially the same; thus, the following description ofthe second gear assembly 804 applies equally to the first gear assembly802.

The second gear assembly 804 includes a rack member 806 supported by alead screw 808. The lead screw 808 can be rotated for fine/gradualadjustment of the driven element 710. Rotation of the lead screw 808 asindicated by arrow 810 causes the rack member 806 to translate along thelead screw 808 as indicated by arrow 812. The direction in which therack member 806 travels relative to the rotation direction of the leadscrew 808 will depend on the selected threading direction of the leadscrew 808, which can vary for different embodiments. As the rack member806 travels translationally along the lead screw 808, the rack member806 engages with gear teeth of the second gear 738 causing the secondgear 738 to rotate as indicated by arrow 814.

The second gear assembly 804 also includes a first acute adjustmentblock 816. The block 816 is part of an acute adjustment assembly 818that also includes an acute adjustment block 820 of the first gearassembly 802. The acute adjustment assembly 818 includes a lock member822. As shown in FIG. 10A, the adjustment blocks 816 and 820 includeteeth that can mate with teeth of the lock member 822. As indicated inFIG. 10B, the lock member 822 can be pulled away from the adjustmentblocks 816 and 820 in order to unlock the acute adjustment assembly 818.The lock member 822 can be pushed against the adjustment blocks 816 and820 (position shown in FIG. 10A) in order to lock the acute adjustmentassembly 818. Thus, the lock member 822 can be pulled away from theadjustment blocks 816 and 820 in order to unlock the acute adjustmentassembly 818 and make acute adjustments to the driven element 710. Whilethe lock member 822 is pulled away from the adjustment blocks 816 and820, the adjustment blocks 816 and 820 can travel translationally, andindependently of each other, in the directions indicated by arrows 824and 826. The lead screw 808 is fixed relative to the adjustment block816 such that the lead screw 808 translates with the adjustment block816. The threads of the lead screw 808 carry the rack member 806 suchthat, if the lead screw is not rotating, the rack member 806 translatesin directions 812 with the lead screw 808 and the adjustment block 816.As the rack member 806 travels translationally with the lead screw 808and adjustment block 816, the rack member 806 engages with gear teeth ofthe second gear 738 causing the second gear 738 to rotate as indicatedby arrow 814. This allows for a more acute adjustment of the drivenelement 710 about the first rotational axis 620 as compared to moregradual adjustments that can be made as described above by rotating thelead screw 810.

As mentioned above, the first gear assembly 802 can be identical orsubstantially the same as the second gear assembly 804. Thus, the drivenelement 710 can be acutely and gradually adjusted about the secondrotational axis 626 via the first gear 718, first drive arm 712, andball joint 706 using the first gear assembly 802 and acute adjustmentassembly 818 in the same manner as describe above in connection with thesecond gear assembly 804.

The locking member 822 simultaneously engages and locks both of theadjustment blocks 816 and 820 when pushed in (direction into the page asindicated by direction 830 in FIG. 10B), and simultaneously disengagesand unlocks both of the adjustment blocks 816 and 820 when pulled out(direction into the page as indicated by direction 832 in FIG. 10B).Thus, when the locking member 822 is moved to the unlocking position,the driven element 710 can be acutely adjusted along both the first andsecond rotational axes 620 and 626. In alternative embodiments, separatelocking members 822 can be provided for each of the adjustment blocks816 and 820. Such an embodiment allows for acute adjustment of only oneof the rotational axes 620 and 626 at a time by unlocking only aselected one of the two locking members 822, or simultaneous acuteadjustments by unlocking both of the locking members 822.

FIG. 11 shows an alternative second gear assembly 804 a that can be usedwith the joint 800. The first gear assembly 802 can be similarlymodified. The gear assembly 804 a also allows for acute and finer ormore gradual adjustments.

The second gear assembly 804 a includes the rack member 806 supported byan alternative lead screw 808 a. The lead screw 808 a includes ahelically threaded portion 850 that supports the rack member 806. Thelead screw 808 a also includes a cylindrically cut portion 852. The leadscrew 808 a can be rotated for fine/gradual adjustment of the drivenelement 710. Rotation of the lead screw 808 a as indicated by arrow 810in FIG. 10B causes the rack member 806 to translate along the lead screw808 a as indicated by arrow 812 in FIG. 10B. The direction in which therack member 806 travels relative to the rotation direction of the leadscrew 808 a will depend on the selected threading direction of thethreaded portion 850 of the lead screw 808 a, which can vary fordifferent embodiments. As the rack member 806 travels translationallyalong the lead screw 808 a, the rack member 806 engages with gear teethof the second gear 738 causing the second gear 738 to rotate asindicated by arrow 814 in FIG. 10B.

The second gear assembly 804 a also includes an alternative acuteadjustment assembly 818 a that includes a lock member 854 and thecylindrically cut portion 852 of the lead screw 808 a. The lock member854 can be controlled to engage or disengage the cylindrical cuts of thecylindrically cut portion 852 of the lead screw 808 a. The lock member854 includes teeth that can mate with the cylindrical cuts of thecylindrically cut portion 852 of the lead screw 808 a. The lock member854 can be pulled away from the cylindrically cut portion 852 of thelead screw 808 a in order to unlock the acute adjustment assembly 818 aand thereby allow for acute adjustments of the second gear assembly 804a. The lock member 854 can be moved to engage the cylindrically cutportion 852 of the lead screw 808 a (position shown in FIG. 11) in orderto lock the acute adjustment assembly 818 a. Thus, the lock member 854can be pulled away from the cylindrically cut portion 852 of the leadscrew 808 a in order to unlock the acute adjustment assembly 818 a andmake acute adjustments to the driven element 710. While the lock member854 is pulled away from the cylindrically cut portion 852 of the leadscrew 808 a, the lead screw 808 a can travel translationally in thedirections indicated by arrow 856. The threaded portion 850 of the leadscrew 808 a carry the rack member 806 such that, if the lead screw 808 ais not rotating, the rack member 806 translates in directions 856 withthe lead screw 808 a. As the rack member 806 travels translationallywith the lead screw 808 a, the rack member 806 engages with gear teethof the second gear 738 causing the second gear 738 to rotate asindicated by arrow 814 in FIG. 10B. This allows for a more acuteadjustment of the driven element 710 about the first rotational axis 620as compared to more gradual adjustments that can be made as describedabove by rotating the lead screw 810.

As mentioned above, an alternative first gear assembly 802 can beidentical or substantially the same as the alternative second gearassembly 804 a. Thus, the driven element 710 can be acutely andgradually adjusted about the second rotational axis 626 via the firstgear 718, first drive arm 712, and ball joint 706 using the first gearassembly 802 and acute adjustment assembly 818 a in the same manner asdescribe above in connection with the second gear assembly 804 a.

Still further embodiments of multiple-axis joints include embodimentsthat combine various elements of the first through sixth embodimentjoints 300, 400, 500, 600, 700, and 800. For example, the joints 300,400, and 500 can be modified to include one or more gear assemblies,such as gear assemblies 616, 618, 716, 736, 802, and 804, and/or acuteadjustment assemblies, such as acute adjustment assembly 818. Morespecifically, any of the gear assemblies 616, 618, 716, 736, 802, and804 can be used to drive any of the gears 312, 314, 414, and 514. Thegear assemblies 616, 618, 716, 736, 802, and 804 constitute examples ofdrive systems that can be driven manually, by way of a handle, knob,removable tool, key, or any other implement suitable for allowing aperson to make manual adjustments for driving the driven element (suchas driven element 316, 426, 526, 606, or 710) in a desired direction.

Any of the multiple-axis joints 300, 400, 500, 600, 700, and 800 andvariations thereof can be used as the first joint 122 and/or the secondjoint 124 of the fixator ring system 100 or the fixator assembly 200.Still further embodiments of fixator ring systems that can include anyof the multiple-axis joints described herein are described below inconnection with FIGS. 12-14.

FIG. 12 shows a perspective view of a first alternative embodiment of anexternal fixator ring system, generally designated as external fixatorring system 900. The fixator ring system 900 includes a first fixatorring 902 a and a second fixator ring 902 b, which serve as examples offixator base elements. The fixator rings 902 a and 902 b both include aplurality of strut mounting positions 904. The fixator rings 902 a and902 b are connected by a pair of connection struts 906 and 908. In thisembodiment, both of the struts 906 and 908 are active struts. While twoactive struts 906 and 908 are shown, alternative embodiments can includemore or fewer active struts.

The first fixator ring 902 a includes a top surface 912 and an opposingbottom surface (not shown). The top surface 912 includes numerous holes916 that extend through the top surface 912 to the bottom surface (notshown). The holes 916 may be used for attachment of wire and half pinfixation elements (bolts), threaded or telescopic connection rods,plates, posts or other device connection elements to the first fixatorring 902 a. The outer side surface 920 of the first fixator ring 902 acan include numerous threaded apertures (not shown) that provideadditional attachment points for struts or other connection elements(not shown). The second fixator ring 902 b can be identical or similarto the first fixator ring 902 a.

Although the shape of the fixator rings 902 a and 902 b as shown FIG. 12is substantially circular, the shape of the fixator rings 902 a and 902b can vary to accommodate the physical contour of various body parts towhich the fixation system 900 would be attached. For example, thefixator rings 902 a and 902 b can be fixator base elements configured tohave an oval shape, D-shape, U-shape, C-shape, a polygon, or otherirregular shapes. In some exemplary embodiments, an elliptical fixatorring (not shown) may be particularly advantageous. The insertion of pinsor wires into a patient's limb can cause the surrounding tissue to swellunevenly, and in such a case, an elliptical fixator ring can accommodatethe uneven swelling better than a circular ring can. The fixator rings902 a and 902 b may be fixator base elements that form a complete ring(full ring) or a segment or portion of a ring (e.g., half ring, ⅓ ring,¼ ring, ⅜ ring, ⅝ ring, ⅔ ring, ¾ ring, and other) that is either usedalone or joined with other segments or portions of the ring to form afixator ring (not shown). The fixator rings 902 a and 902 b may befixator base elements constructed of any material that provides thestructural rigidity necessary for fixation such as metal, alloy, carbonfiber, plastic, ceramic and so forth.

The strut 906 includes a first joint 922 and a second joint 924connected by a center portion 926. The first joint 922 and second joint924 are embodiments of multiple axis joints, such as the fourth, fifth,or sixth embodiment joints 600, 700, and 800, that include a generallyvertical driven element. The first joint 922 includes a first drivenelement 928 that connects to one of the strut mounting positions 904 ofthe first fixator ring 902 a. As discussed herein, the driven element928 can be angularly and/or rotationally repositioned relative to thecenter portion 926 of the strut 906. The second joint 924 includes asecond driven element 930 that connects to one of the strut mountingpositions 904 of the second fixator ring 902 b. As discussed herein, thedriven element 930 can be angularly and/or rotationally repositionedrelative to the center portion 926 of the strut 906. The connectionstrut 908 also includes first and second joints 922 and 924 and can beidentical to the first connection strut 906.

The joints 922 and 924 of the struts 906 and 908 can be manipulated, forexample by hand or using a tool such as a wrench, to angulate and/orrotate (depending on the joint) the driven elements 928 and 930. Forexample, the joints 922 and 924 can include set screws or the like onthe housings thereof for allowing insertion of a wrench, screwdriver, orother such tool so that the user can drive the gears/gear assemblies(such as gears 312, 314, 414, and 514 and/or gear assemblies 616, 618,716, 736, 802, and 804) and thereby reposition the driven elements 928and 930.

The center portion 926 can be a strut body such as center portion 126 ofthe fixator assembly 200 shown in FIG. 2, which includes variousadjustable elements in order to allow for six degrees of freedom.Combining two of the multiple-axis joints described herein with such astrut body can allow for effectively moving two bone segments, fixatorbase elements, or other elements through all six degrees of freedom.

Two struts such as struts 906 and 908 can thus be used with rings 902 aand 902 b in order to move two bone segments relative to one another.First, the rings 902 a would be attached to bone segments with fixationelements such as half pins or k-wires. Second, the struts 906 and 908would be unlocked and attached to the rings 902 a and 902 b with anangular separation preferably of greater than 90 degrees and an acuteadjustment would be made, if necessary. Third, the struts 906 and 908would be locked into an active-locked state so as to hold the bonesegments in place. Next, gradual adjustment could be made over time byadjusting the driven elements 928 and 930 of the struts 906 and 908while the struts 906 and 908 are in active-locked states. This gradualadjustment over time could move two bone segments relative to each otherin all six degrees of freedom.

FIG. 13 shows a perspective view of a second alternative embodiment ofan external fixator ring system, generally designated as externalfixator ring system 1100. The fixator ring system 1100 includes a firstfixator ring 1102 a and a second fixator ring 1102 b, which serve asexamples of fixator base elements. The fixator rings 1102 a and 1102 bboth include a plurality of strut mounting positions 1104. The fixatorrings 1102 a and 1102 b are connected by a pair of active struts 906 and908, which can be identical to the active struts 906 and 908 describedabove, wherein like elements of active struts 906 and 908 have retainedlike element numbers. The fixator rings 1102 a and 1102 b are alsoconnected by a pair of passive struts 1130 and 1132, which can be thesame as, or similar to, passive struts 108 and 110.

The first fixator ring 1102 a includes an outer side surface 1112 a andan opposing inner side surface 1112 b. Numerous holes 1116 that extendthrough the outer side surface 1112 a to the inner side surface 1112 b.The holes 1116 may be used for attachment of threaded or telescopicconnection rods 1130 and 1132 between the first and second fixator rings1102 a and 1102 b. The holes 1116 may also be used for attachment ofwire and half pin fixation elements (bolts), additional threaded ortelescopic connection rods, plates, posts or other device connectionelements to the first fixator ring 1102 a. The second fixator ring 1102b can be identical or similar to the first fixator ring 1102 a.

Although the shape of the fixator rings 1102 a and 1102 b as shown FIG.13 is substantially circular, the shape of the fixator rings 1102 a and1102 b can vary to accommodate the physical contour of various bodyparts to which the fixation system 1100 would be attached. For example,the fixator rings 1102 a and 1102 b can be fixator base elementsconfigured to have an oval shape, D-shape, U-shape, C-shape, a polygon,or other irregular shapes. In some exemplary embodiments, an ellipticalfixator ring (not shown) may be particularly advantageous. The insertionof pins or wires into a patient's limb can cause the surrounding tissueto swell unevenly, and in such a case, an elliptical fixator ring canaccommodate the uneven swelling better than a circular ring can. Thefixator rings 1102 a and 1102 b may be fixator base elements that form acomplete ring (full ring) or a segment or portion of a ring (e.g., halfring, ⅓ ring, ¼ ring, ⅜ ring, ⅝ ring, ⅔ ring, ¾ ring, and other) that iseither used alone or joined with other segments or portions of the ringto form a fixator ring (not shown). The fixator rings 1102 a and 1102 bmay be fixator base elements constructed of any material that providesthe structural rigidity necessary for fixation such as metal, alloy,carbon fiber, plastic, ceramic and so forth.

The strut 906 includes a first joint 922 and a second joint 924connected by a center portion 926. The first joint 922 and second joint924 are embodiments of multiple axis joints, such as the fourth, fifth,or sixth embodiment joints 600, 700, and 800, that include a generallyvertical driven element. The first joint 922 includes a first drivenelement 928 that connects to one of the holes 916 of the first fixatorring 902 a. As discussed herein, the driven element 928 can be angularlyand/or rotationally repositioned relative to the center portion 926 ofthe strut 906. The second joint 924 includes a second driven element 930that connects to one of the holes 916 of the second fixator ring 902 b.As discussed herein, the driven element 930 can be angularly and/orrotationally repositioned relative to the center portion 926 of thestrut 906. The connection strut 908 also includes first and secondjoints 922 and 924 and can be identical to the first connection strut906.

The joints 922 and 924 of the struts 906 and 908 can be manipulated, forexample by hand or using a tool such as a wrench, to angulate and/orrotate (depending on the joint) the driven elements 928 and 930. Forexample, the joints 922 and 924 can include set screws or the like onthe housings thereof for allowing insertion of a wrench, screwdriver, orother such tool so that the user can drive the gears/gear assemblies(such as gears 312, 314, 414, and 514 and/or gear assemblies 616, 618,716, 736, 802, and 804) and thereby reposition the driven elements 928and 930.

The center portion 926 can be a strut body such as center portion 126 ofthe fixator assembly 200 shown in FIG. 2, which includes variousadjustable elements in order to allow for six degrees of freedom.Combining two of the multiple-axis joints described herein with such astrut body can allow for effectively moving two bone segments, fixatorbase elements, or other elements through all six degrees of freedom.

The two struts 906 and 908 can thus be used with a set of rings 1102 aand 1102 b in order to move two bone segments relative to one another.First, the rings 1102 a and 1102 b would be attached to the bonesegments with fixation elements such as half pins or k-wires. Second,the two struts 906 and 908 would be unlocked and attached to the rings1102 a and 1102 b with an angular separation preferably greater than 90degrees and an acute adjustment would be made, if necessary. Third, thestruts 906 and 908 would be locked to hold the bone segments in place.Fourth, the passive struts 1130 and 1132 would be attached between thetwo rings 1102 a and 1102 b for additional support against tissue andother forces. Next, gradual adjustments could be made by unlocking thepassive struts 1130 and 1132, adjusting the driven elements 928 and 930of the active struts 906 and 908, and then once again locking thepassive struts 1130 and 1132. This gradual adjustment over time couldmove two bone segments relative to each other in all six degrees offreedom. The passive struts 1130 and 1132 are removable such that duringx-rays or other scenarios when increased access or visibility isnecessary the passive struts 1130 and 1132 can be removed, and theactive struts 906 and 908 are sufficient for rigidly maintaining therelative positions of the rings 1102 a and 1102 b.

FIGS. 14A through 14C show an embodiment of a passive support strut 1200that can be used as passive struts 108 and 110 in FIG. 1, and passivestruts 1132 and/or 1130 in FIG. 13. The passive support strut 1200includes multiple joint members 1202 that are nested within one another,as shown in FIG. 14C, between a pair of attachment studs 1208 a and 1208b. The attachment studs 1208 a and 1208 b can be used to attach thepassive support strut 1200 to fixator base elements or other devices.For example, the attachment studs can be threaded studs that can passthrough a hole in a fixator ring and secured in place using a threadednut. Alternatively, the attachment studs can be configured pass througha hole in a fixator ring and secured in place using a cotter pin. Stillfurther embodiments can use any desirable type of attachmentconfiguration.

The joint members 1202 can rotate in all three orthogonal degrees offreedom relative to each other in order to change length and directionand to follow fixator base elements as they are driven in all sixdegrees of freedom by one or more active struts. The passive supportstrut 1200 can be locked into a rigid state such that the rings 102 aand 102 b are fixed relative to each other, and unlocked into a freestate such that acute adjustments can be made to the relative positionsof the rings 102 a and 102 b. As shown in FIGS. 14B, the attachmentstuds 1208 a and 1208 b are each connected to a central locking element1206 by a connection element 1210 that passes through channels 1212 ofthe joint members 1202. The connection element 1210 can be a cable,cord, string, wire, or the like. The central locking element 1206 isdisposed within a central support member 1204. Rotation of the centrallocking element 1206 can wind or unwind the connection element 1210,thereby increasing or decreasing the compression on the joint members1202 between the central support member 1204 and the attachment studs1208 a and 1208 b. The locking element 1206 can be a spool, cam, orother suitable device. The joint members 1202 can be compressed togetherby operation of the locking element 1206 on the connection element 1210such that friction between the joint elements 1202 prohibits relativemovement between the joint elements 1202. The passive stud 1200 can thusbe locked. The passive stud 1200 can be unlocked by operating thelocking element 1206 in order to reduce the compression between theattachment studs 1208 a, 1208 b and the central support member 1204. Insome embodiments, the central locking element 1206 can include slots,grooves, detents, or the like for preventing the central locking element1206 from rotating due to the compressive forces of the connectionelement 1210 while the passive support strut 1200 is locked. In someembodiments, the central locking element 1206 can include a handle,lever, or other such element for allowing a technician to lock/unlockthe passive support strut 1200. In some embodiments, the central lockingelement 1210 can include a slot, key, or otherwise be configured to beoperated by a removable tool.

FIG. 15 shows an alternative embodiment of a support strut 1300 that canbe used in place of passive struts 108 and 110 in FIG. 1, and passivestruts 1132 and/or 1130 in FIG. 13. The support strut 1300 includesfirst and second joints 1302 a and 1302 b attached to opposing ends of acentral portion 1304. In some embodiments, the central portion 1304 canbe lengthwise adjustable. The first and second joints 1302 a and 1302 bcan be attached to a hole in a fixator ring and secured in place using athreaded screw, bolt, combination of a nut and bolt, or any otherdesired attachment means. The first and second joints 1302 a and 1302 bcan include any desired type of joint that allows for rotation in threedegrees of freedom, including heim joints, universal joints, balljoints, or other joints.

All of the compositions and/or methods disclosed and claimed herein canbe made and executed without undue experimentation in light of thepresent disclosure. While the compositions and methods of this inventionhave been described in terms of preferred embodiments, it will beapparent to those of skill in the art that variations may be applied tothe compositions and/or methods and in the steps or in the sequence ofsteps of the method described herein without departing from the concept,spirit and scope of the invention. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the spirit, scope and concept of the invention as defined by theappended claims.

What is claimed is:
 1. A fixator system, comprising: a first fixatorbase element; a second fixator base element; a first active strutconnected between the first fixator base element and the second fixatorbase element; and a first passive strut connected between the firstfixator base element and the second fixator base element; wherein thefirst passive strut is configured to be placed into a passive lockedstate such that the first passive strut is non-adjustable and resistsrelative positional changes between the first and second fixator baseelements, and placed into an unlocked state such that the first passivestrut freely allows relative positional changes between the first andsecond fixator base elements; wherein the first active strut isconfigured to be placed into an active locked state such that the firstactive strut resists relative positional changes between the first andsecond fixator base elements, and placed into an unlocked state suchthat the first active strut freely allows relative positional changesbetween the first and second fixator base elements; wherein the firstactive strut is configured to allow relative positional changes betweenthe first and second fixator base elements while maintaining rigiditywhile the first active strut is in the active locked state; and whereinthe first active strut is configured to allow adjustment of an overalllength of the first active strut when the first active strut is in theactive locked state.
 2. The fixator system of claim 1, furthercomprising a second active strut connected between the first fixatorbase element and the second fixator base element; wherein the secondactive strut is configured to be placed into an active locked state suchthat the second active strut resists relative positional changes betweenthe first and second fixator base elements, and placed into an unlockedstate such that the second active strut freely allows relativepositional changes between the first and second fixator base elements;wherein the second active strut is configured to allow relativepositional changes between the first and second fixator base elementswhile maintaining rigidity while the second active strut is in theactive locked state; and wherein the second active strut is configuredto allow adjustment of an overall length of the second active strut whenthe second active strut is in the active locked state.
 3. The fixatorsystem of claim 1, further comprising a second passive strut connectedbetween the first fixator base element and the second fixator baseelement; wherein the second passive strut is configured to be placedinto a passive locked state such that the second passive strut isnon-adjustable and resists relative positional changes between the firstand second fixator base elements, and placed into an unlocked state suchthat the second passive strut freely allows relative positional changesbetween the first and second fixator base elements.
 4. The fixatorsystem of claim 1, wherein the first active strut includes a jointcomprising a driven element attached to the first fixator base element,a first drive system that rotates the driven element about a first axisof rotation, and a second drive system that rotates the driven elementabout a second axis of rotation, wherein the first and second axesintersect at a common point of rotation of the driven element.
 5. Thefixator system of claim 1, wherein the first active strut is configuredto be placed into a passive locked state such that the first activestrut is non-adjustable and resists relative positional changes betweenthe first and second fixator base elements.
 6. A strut for a fixatorsystem, the strut comprising: a first joint; a second joint; and acentral portion connected between the first and second joints, thecentral portion being adjustable in at least two degrees of freedom;wherein the strut is configured to be placed into an active locked statesuch that the strut resists relative positional changes between thefirst and second joints, and placed into an unlocked state such that thestrut freely allows relative positional changes between the first andsecond joints; wherein the strut is configured to allow for relativepositional changes between the first joint and the second joint whilemaintaining rigidity while the strut is in the active locked state; andwherein the strut is configured to allow for adjustment of an overalllength of the strut when the strut is in the active locked state.
 7. Thestrut of claim 6, wherein the first joint further comprises: a firstdrive system that rotates a first driven element of the first jointabout a first axis of the first joint; and a second drive system thatrotates the first driven element about a second axis of the first joint;wherein the first and second axes intersect about a first common pointof rotation of the first driven element.
 8. The strut of claim 6,wherein the central portion is lengthwise adjustable.
 9. The strut ofclaim 6, wherein the strut is configured to be placed into a passivelocked state such that the strut is non-adjustable and resists relativepositional changes between the first and second joints.
 10. A fixatorsystem, comprising: a first fixator base element; a second fixator baseelement; a first active strut connected between the first fixator baseelement and the second fixator base element; and a first passive strutconnected between the first fixator base element and the second fixatorbase element; wherein the first passive strut is configured to be placedinto a passive locked state such that the first passive strut isnon-adjustable and resists relative positional changes between the firstand second fixator base elements, and placed into an unlocked state suchthat the first passive strut freely allows relative positional changesbetween the first and second fixator base elements; wherein the firstactive strut is configured to be placed into an active locked state suchthat the first active strut resists relative positional changes betweenthe first and second fixator base elements, placed into a passive lockedstate such that the first active strut is non-adjustable and resistsrelative positional changes between the first and second fixator baseelements, and placed into an unlocked state such that the first activestrut freely allows relative positional changes between the first andsecond fixator base elements; and wherein the first active strut isconfigured to allow relative positional changes between the first andsecond fixator base elements while maintaining rigidity while the firstactive strut is in the active locked state.
 11. The fixator system ofclaim 10, further comprising a second active strut connected between thefirst fixator base element and the second fixator base element; whereinthe second active strut is configured to be placed into an active lockedstate such that the second active strut resists relative positionalchanges between the first and second fixator base elements, placed intoa passive locked state such that the second active strut isnon-adjustable and resists relative positional changes between the firstand second fixator base elements, and placed into an unlocked state suchthat the second active strut freely allows relative positional changesbetween the first and second fixator base elements; and wherein thesecond active strut is configured to allow relative positional changesbetween the first and second fixator base elements while maintainingrigidity while the second active strut is in the active locked state.12. The fixator system of claim 10, further comprising a second passivestrut connected between the first fixator base element and the secondfixator base element; wherein the second passive strut is configured tobe placed into a passive locked state such that the second passive strutis non-adjustable and resists relative positional changes between thefirst and second fixator base elements, and placed into an unlockedstate such that the second passive strut freely allows relativepositional changes between the first and second fixator base elements.13. The fixator system of claim 10, wherein the first active strutincludes a joint comprising a driven element attached to the firstfixator base element, a first drive system that rotates the drivenelement about a first axis of rotation, and a second drive system thatrotates the driven element about a second axis of rotation, wherein thefirst and second axes intersect at a common point of rotation of thedriven element.
 14. The fixator system of claim 10, wherein the firstactive strut is configured to allow adjustment of an overall length ofthe first active strut when the first active strut is in the activelocked state.
 15. A strut for a fixator system, the strut comprising: afirst joint; a second joint; and a central portion connected between thefirst and second joints, the central portion being adjustable in atleast two degrees of freedom; wherein the strut is configured to beplaced into an active locked state such that the strut resists relativepositional changes between the first and second joints, placed into apassive locked state such that the strut is non-adjustable and resistsrelative positional changes between the first and second joints, andplaced into an unlocked state such that the strut freely allows relativepositional changes between the first and second joints; and wherein thestrut is configured to allow for relative positional changes between thefirst joint and the second joint while maintaining rigidity while thestrut is in the active locked state.
 16. The strut of claim 15, whereinthe first joint further comprises: a first drive system that rotates afirst driven element of the first joint about a first axis of the firstjoint; and a second drive system that rotates the first driven elementabout a second axis of the first joint; wherein the first and secondaxes intersect about a first common point of rotation of the firstdriven element.
 17. The strut of claim 15, wherein the central portionis lengthwise adjustable.
 18. The strut of claim 15, wherein the strutis configured to allow for adjustment of an overall length of the strutwhen the strut is in the active locked state.